First of all, there was no need of writing this matter down, since this issue had been mentioned by God and his Prophet Mohammad too many times and the most conspicuous one was, better to say is Ghadir Khom day. When Prophet Mohammad; how ever, faced with opposition and disobeying of enemies in order not to join Osame troop, determined to emphasize on this matter once more again and write it down. After that while Prophet was sick and laying down in bed, ordered to provide paper and pen to write Imam Alis sanctity down, where as Omar Ibn Khatab did not allow this take part and impolitely and in a form of insulting Prophet, said that, Our Prophets words are just delirium and our book Koran will suffice us. To clarify this matter you can even refer to several valid books of Sunni like Saheh Bokhari. Omar said that our book Koran is enough for us while in well-known tradition- Sagalin- Prophet himself has said, if you want to live in prosperity refer to both Koran and Imams (My family).In excess, in Koran God says Prophet never says nonsense words and what he says are nothing but Gods words. Thus, Prophet Mohammad wanted to write Imam Alis Imamate down in the last moment of his life but Omar Ibn Khatab was such prevention.